1. Field of the Invention
The present invention relates to a process for producing a propylene oligomer or an oligomer of propylene and an olefin or more than two olefins other than propylene, which can be effectively used as starting materials for chemical synthesis, starting materials for polymers, lubricating oil substrates, cosmetics and the like.
2. Related Art
Propylene oligomers and oligomers of propylene and an olefin or more than two olefins other than propylene have been used as starting materials for chemical synthesis, starting materials for polymers, lubricating oil substrates, cosmetics and the like.
As a process for producing the above propylene based oligomers, there have been heretofore known a process which comprises reacting propylene alone or propylene and the other olefin, using a catalyst composed of an alkyl-substituted cyclopentadienyl compound containing zirconium and/or hafnium; and aluminoxane (Japanese Patent Appln. Laid-Open Gazette No. Hei 1-207248; U.S. Pat. No. 4,814,540).
However, in the above-mentioned process, after polymerization, deashing treatment for the resultant product should be sufficiently conducted since the aluminoxane as promotor should be used in a large amount as compared with the amount of the transition metal compound as main catalyst component to provide sufficient activity and a large amount of the aluminum compound is used. Since the aluminoxane is expensive, the amount thereof used should be drastically reduced. It is desirable not to use the aluminoxane.